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Drewell (ドリエル): ingredients, dose and warnings in English

Drewell (ドリエル) is sold in Japan as a designated class 2 medicine: the box reads 第②類医薬品. In 2 tablets: Diphenhydramine Hydrochloride 50 mg. The package insert sets the adult dose at 2 tablets, once a day, for ages 15 and over.

Updated

50mgDiphenhydramine Hydrochloride per dose
2 tabletsAdult dose
1Doses a day

第②類医薬品 · Designated class 2要確認 · Shop checks first

What is in Drewell

The package insert lists 1 active ingredient in 2 tablets. The middle column is how each one is written on the Japanese box.

Drewell: active ingredients in 2 tablets, from the Japanese package insert
IngredientName on the boxAmount
Diphenhydramine Hydrochlorideジフェンヒドラミン塩酸塩50 mg
Additives, as written on the package insert (Japanese)

クロスカルメロースNa、無水ケイ酸、セルロース、乳糖、ヒドロキシプロピルセルロース、ヒプロメロース、マクロゴール、ステアリン酸Mg、タルク、酸化チタン

The maker publishes an English package insert for DREWELL: SSP: DREWELL (English package insert). This page translates the current Japanese package insert on PMDA.

Source: PMDA (Pharmaceuticals and Medical Devices Agency) — ドリエル: package insert (添付文書) · SSP — DREWELL: English package insert

What the package insert lists it for

The approved wording of the Japanese package insert, translated. It is what the product is sold for, not advice on what to take.

  • Relief of the following symptoms of temporary sleeplessness: difficulty falling asleep, light sleep

The dose, as written on the package insert

Translated line by line from the directions and dosage (用法・用量) section.

Diphenhydramine Hydrochloride per dose
50 mg
Adult dose
2 tablets
Doses a day
1
Age
15 and over
  • When you have difficulty falling asleep or your sleep is light, take the following single dose 1 time a day before bedtime with water or lukewarm water.
Dose by age, as written on the package insert
AgeSingle dose
Adults (15 and over)2 tablets
Under 15Do not take

Notes on the directions

  • (1) Follow the directions and dosage exactly.
  • (2) If you take more than 2 tablets per dose, unpleasant symptoms such as your nerves becoming overexcited may appear, and you may instead become unable to sleep.
  • (3) Do not take it at times other than before bedtime.
  • (4) How to take out the tablets
  • Press the raised part of the PTP sheet containing the tablet firmly with your fingertip to break the aluminium foil on the back, then remove the tablet and take it. (Accidentally swallowing it as it is can lead to unexpected accidents, such as it piercing the mucous membrane of the oesophagus.)

Do not

The package insert opens with what you must not do.

(If you do not follow these, your current symptoms may get worse, and side effects or accidents become more likely.)

1. Do not take it if you are one of the following people

  • (1) Women who are pregnant or think they may be pregnant.
  • (2) Children under 15.
  • (3) People who have sleeplessness on a daily basis.
  • (4) People who have been diagnosed with insomnia.

2. Do not use any of the following medicines while taking this medicine

  • Other sleep aids and sedatives, cold medicines, pain and fever medicines, cough medicines, oral medicines containing antihistamines, etc. (oral medicines for rhinitis, motion sickness medicines, allergy medicines, etc.)

3. Do not drive or operate machinery after taking it

  • (It may make you drowsy and cause an accident. Also, if taking this medicine makes drowsiness continue into the next day or makes you feel tired, do not drive or operate machinery until these symptoms have gone.)

4. Women who are breastfeeding: do not take this medicine, or avoid breastfeeding if you take it

5. Do not drink alcohol before or after taking it

6. Limit taking it to times when you have difficulty falling asleep or your sleep is light, and do not take it continuously

Ask a doctor, pharmacist or registered salesperson

The package insert says to ask for advice in these cases.

1. If you are one of the following people, ask a doctor, pharmacist or registered salesperson for advice before taking it

  • (1) People who are receiving treatment from a doctor.
  • (2) Older people. (In older people, drowsiness may appear strongly, or, conversely, symptoms such as the nerves becoming overexcited may appear.)
  • (3) People who have had allergic symptoms caused by medicines etc.
  • (4) People who have the following symptoms. Difficulty urinating
  • (5) People who have been diagnosed with the following. Glaucoma, enlarged prostate

2. If the following symptoms appear after taking it, they may be side effects, so stop taking it immediately and ask a doctor, pharmacist or registered salesperson for advice, taking this leaflet with you

Possible side effects, by part of the body
Skin
rash/redness, itching
Digestive system
stomach pain, nausea/vomiting, loss of appetite
Nervous system
dizziness, headache, a heavy feeling in the head on waking, daytime drowsiness, feeling unwell, nervousness, temporary impaired consciousness (reduced attention, symptoms like being half asleep, reduced judgement, abnormal speech and behaviour, etc.)
Circulatory system
palpitations
Urinary system
difficulty urinating
Other
lethargy

3. The following symptoms may appear after taking it, so if these symptoms continue or get worse, stop taking it and ask a doctor, pharmacist or registered salesperson for advice, taking this leaflet with you

  • Dry mouth, diarrhoea

4. If your symptoms do not improve after taking it 2 to 3 times, stop taking it and ask a doctor, pharmacist or registered salesperson for advice, taking this leaflet with you

Other precautions

  • Drowsiness may continue into the next day, or you may feel tired.

Who can sell it in Japan

The Drewell box carries the class 第②類医薬品, which decides who may sell it.

On the box
第②類医薬品 (Designated class 2). The box reads 第2類医薬品 with the 2 in a square, or 第②類医薬品.
Who can sell it
A pharmacist or a registered salesperson may sell it.

要確認: the shop checks before selling this one.Drewell contains Diphenhydramine Hydrochloride. From 1 May 2026, medicines taken by mouth with this ingredient are designated abuse-prevention medicines (指定濫用防止医薬品).

Source: e-Gov law search (Digital Agency, Japan) — Pharmaceutical and Medical Device Act (医薬品医療機器等法), current text · e-Gov law search (Digital Agency, Japan) — Enforcement Regulations of the Pharmaceutical and Medical Device Act (施行規則), current text · Ministry of Health, Labour and Welfare — Designated class 2 medicines (指定第２類医薬品について) · Ministry of Health, Labour and Welfare — Designated abuse-prevention medicines, Notice No. 32 of 2026 (告示第32号) · Ministry of Health, Labour and Welfare — Quantity for designated abuse-prevention medicines, Notice No. 33 of 2026 (告示第33号) · Ministry of Health, Labour and Welfare — Selling designated abuse-prevention medicines (医薬発1226第16号, 26 December 2025) · Ministry of Health, Labour and Welfare — Q&A on selling designated abuse-prevention medicines (30 January 2026)

Taking it home

Frequently asked questions

How much Diphenhydramine Hydrochloride is in Drewell?

50 mg in a dose of 2 tablets, according to the Japanese package insert.

How much Drewell can an adult take in a day?

The package insert sets the adult dose at 2 tablets, once a day.

Can children take Drewell?

No. The package insert says it is not to be taken under 15.

Do I need a pharmacist to buy Drewell?

Drewell is a designated class 2 medicine (第②類医薬品). A pharmacist or a registered salesperson may sell it.

Why does the shop check before selling Drewell?

It contains Diphenhydramine Hydrochloride, one of the 8 ingredients that make a medicine taken by mouth a designated abuse-prevention medicine (指定濫用防止医薬品) from 1 May 2026. The shop gives the information in writing and checks what you have bought there and at other shops.

What is Drewell called in Japanese?

ドリエル. The Drewell box also carries the class 第②類医薬品.

Related items

Package insert in Japanese: PMDA

Sources for this page

Back to Japanese OTC medicine

Compiled by Japan Japan !! · Updated October 3, 2026